Is anger a sin, or does God design anger in us for a purpose? What is the evidence?

Anger is not a sin, except being angry enough to want to harm someone (Mt 5:21-22).

Ephesians 4:26 “In your anger do not sin”: Do not let the sun go down while you are still angry,

We are made in God's image and he gets angry sometimes.

Potato chips were invented because of anger. A cook got tired of a customer complaining that his fried potatoes were too thick. So out of anger he sliced them up as thin as he could and served them, thinking he would tick the customer off. The were a hit and the rest is history.

In Judaism, anger in of itself is not a sin, however, what it can possibly result in, if left unchecked, is the issue.

Which is why in Jewish religious thought people are counciled to turn away from anger.

For example, Maimonides said that one should take the "middle path" (i.e. neither extreme) except in two cases, one being anger (i.e. one should bend to the opposite direction) the other being haughtiness.

Man’s expression of anger may be proper if it is based on principle. One may rightly express righteous indignation. We are commanded to “abhor what is wicked.” The Bible provides numerous examples of righteous indignation.​ However, the anger of man is more often unjustified and is many times uncontrolled. It is often based on insufficient cause and expressed without due regard for the consequences. After Jehovah had spared Nineveh, Jonah was displeased, “and he got to be hot with anger.” Jonah lacked mercy and had to be corrected by Jehovah.

Anger, even when justified, if not controlled, may be dangerous, producing bad results. When under heavy provocation a person should control his anger. The complaint and rebelliousness of the Israelites provoked Moses, the meekest man on the earth, to an uncontrolled act of anger in which he failed to sanctify Jehovah, and for which he was punished.​ Fits of anger are classified along with other detestable works of the flesh, such as loose conduct, idolatry, practice of spiritism, and drunken bouts. Such will keep one from inheriting God’s Kingdom. (Ga 5:19-21) Angry talk is to be kept out of the congregation. Men representing the congregation in prayer should be free from feelings of anger and ill will. Christians are commanded to be slow about wrath, being told that man’s wrath does not work out God’s righteousness.

Jesus Christ, when a man on earth, gave us the perfect example. The records of his life do not recount one occasion where he had a fit of uncontrolled anger or where he allowed the lawlessness, rebelliousness, and harassment of the enemies of God to upset his spirit and cause him to reflect such a thing toward his followers or others. On one occasion he was “thoroughly grieved” at the insensibility of the hearts of the Pharisees and looked upon them with indignation. His next act was an act of healing.

It’s not a sin

Since you asked about evidence. there is no evidence:

A) That god exists

B) That god designed anything

C) That god issues commandments

D) That breaking god commandments is a sin

E) That anger is anything other than a completely natural emotional response with no moral connotations

Hope that helps. Rolls eyes

Anger is a built in human response, for a variety of reasons.

When you are in danger, anger is to protect you from an adversary.

Anger sends a clear message to anyone or someone its intended or sent towards.

Anger is necessary for communicating displeasure about a wrong thing especially.

Those are some positives.

Anger's negatives are: sinful and sometimes destructive to other humans.

When its out of control, it can be dangerous beyond repair.

Harmful and Hurtful and irrepairable.

There's such a thing as righteous anger.

Consider Christ's anger at the merchants who turned the temple into a "den of thieves." They had set up shop in the courtyards of the temple and they were fleecing -- excuse the expression -- those who had traveled far and at some expense to worship at the temple.

Constructive anger can sometimes be useful...

Like: being very angry about the way certain people are treated, or about the way we're ruining the environment, to the point of getting out there and deciding to DO something about it! Anger can often translate into that sort of passion...

Also: it can be a good thing in cases where you really need to defend yourself! Like, if you're being abused by your partner, for instance... Sometimes you need to demonstrate, though anger, that you're just NOT going to put up with that sh*t anymore! And if it works..? They'll leave you alone from then on.

Jesus said that everyone who continues wrathful with his brother will be accountable to the court of justice, the local court. According to tradition, these courts were set up in cities with an adult male population of 120 or more.

The judges at such a court had authority to render judgment, even on murder cases. Thus, Jesus was showing that a person who harbors smoldering wrath against his brother is committing a serious sin.

For good reason, the Bible warns against anger, abusive speech, and screaming. Eph. 4:31 Sadly, such conduct often escalates into violence. The world may view angry behavior as normal, but it dishonors our Creator.

How does God view someone who has a violent temper? The Bible warns: “Do not have companionship with anyone given to anger; and with a man having fits of rage you must not enter in.” Proverbs 22:24 Uncontrolled anger often leads to acts of violence.

not necessarily...

there is righteous anger (JESUS and the temple?)

GOD and judgment?

real full blown anger can be temporary insanity...

where you cannot think clearly.

righteous indignation differs.